A display device is provided which displays images by emitting light when a reference voltage is applied to pixels. An average picture level calculation unit of a reference voltage calculation unit in a rectangular wave driving unit of a TFT substrate calculates the value of average picture level, and a ΔV calculation unit of a reference voltage calculation unit calculates a correction amount ΔV of the reference voltage based on the average picture level value. The calculated correction amount ΔV is added to a reference voltage and is used as the voltage of a rectangular wave signal that is output to each pixel from a rectangular wave driving unit. In each pixel in which a data signal corresponding to the grayscale value is stored, an organic EL device emits light in accordance with the rectangular wave signal.